Patent Review: Use of Adsorbent Carbon Microspheres for Treatment of Irritable Bowel Syndrome

Posted on September 27th, 2010Microsphere Expert

United States Patent 7,749,497 was recently issued to Ocera Therapeutics, Inc. (San Diego, CA) regarding the use of adsorbent carbon microspheres for the treatment of irritable bowel syndrome.

The patent invention primarily describes the use of adsorbent carbon microspheres for the treatment of irritable bowel syndrome and symptoms associated with it. Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by altered bowel habits without the presence of detectable structural abnormalities. IBS is fairly common and makes up 20-50% of visits to gastroenterologists. Most commonly, patients have abdominal pain associated with altered bowel habits that consist of constipation, diarrhea, or both. The other group consists of patients with painless diarrhea.

One embodiment disclosed herein includes a method of treating one or more symptoms of irritable bowel syndrome by administering to the subject adsorbent carbon microspheres with a particle size of 0.01mm to about 2 mm to reduce the abdominal discomfort or pain. In one embodiment, the amount of the adsorbent carbon microspheres is sufficient to achieve at least about a 50% reduction in the number of days the subject experiences abdominal pain or discomfort.

In some of the embodiments, the adsorbent carbon microspheres have a particle size of about 0.05mm to about 0.8 mm. In some of the above embodiments, the adsorbent carbon microspheres have a specific surface area of about 700 m.sup.2/g or more as determined by a BET method. In some of the above embodiments, the adsorbent carbon microspheres have a specific surface area of about 700 m.sup.2/g to about 2500 m.sup.2/g as determined by a BET method.

Microsphere Manufacturing Process:

First, a dicyclic or tricyclic aromatic compound or a mixture thereof having a boiling point of 200.degree. C. or more is added as an additive to a pitch such as a petroleum pitch or a coal pitch. The whole is heated and mixed, and then shaped to obtain a shaped pitch. Thereafter, the shaped pitch is dispersed and granulated in hot water at 70 to 180.degree. C., with stirring, to obtain a microspherical shaped pitch. The aromatic additive is extracted and removed from the shaped pitch by a solvent having a low solubility to the pitch but a high solubility to the additive. The resulting porous pitch is oxidized by an oxidizing agent to obtain a porous pitch subject to heat infusibility. The resulting infusible porous pitch is treated at 800 to 1000.degree. C. in a gas flow such as steam or carbon dioxide gas reactive with carbon to obtain a porous carbonaceous substance.

The resulting porous carbonaceous substance is then oxidized in a temperature range of 300 to 800.degree. C., preferably 320 to 600.degree. C., in an atmosphere containing 0.1 to 50% by volume, preferably 1 to 30% by volume, particularly preferably 3 to 20% by volume, of oxygen. The substance is thereafter reduced in a temperature range of 800 to 1200.degree. C., preferably 800 to 1000.degree. C., in an atmosphere of a non-oxidizable gas to obtain the final product. More details of suitable production processes and suitable products may be found in U.S. Pat. Nos. 4,681,764 and 6,830,753 and U.S. Application Publication No. 2005/0112114, filed May 26, 2005, all of which are incorporated herein by reference in their entirety. Suitable adsorbent carbon microspheres are commercially available from Kureha Corp., and is sold in Japan under the trade name KREMEZIN.RTM. (also known as AST-120).

Administration of the Microspheres to the Patient:

For use as described herein, adsorbent carbon microspheres may be administered to the gut of a subject by any suitable means. In one embodiment, the carbon is administered orally. Formulations for oral administration may include, but are not limited to, free flowing microspheres, granules, tablets, sugar-coated tablets, capsules, suspensions, sticks, divided packages, or emulsions. In the case of capsules, gelatin capsules, or if necessary, enteric capsules may be used. The oral dosage administered to a subject may be any amount suitable to achieve the desired therapeutic result. In some embodiments, the oral dosage in the case of a human is about 1 to 20 g of the adsorbent per day.